A new reserve of “combustible ice” has been identified in the South China Sea near the Pearl River mouth basin in what may be a significant step forward in developing the highly-pure fuel as a potential new energy source.

The China Geological Survey made the latest discovery in deep ocean beds in the area, the Guangzhou Daily reported on Sunday.

The government confirmed the presence of combustible ice in eastern seas near the coast of the Pearl River mouth basin three years ago. It said the area could contain the equivalent of 100 to 150 billion cubic metres of natural gas.

However, there are huge challenges in excavating the fuel for commercial use.

These include the ice melting and the gas dispersing as attempts are made to collect it deep under the sea and the danger of land slippage and collapse.

The latest missions were carried out with a remote-controlled diving vessel made in China named Seahorse. It was the first deployment of the vessel, which can dive to depths of 4,500 metres, according to the report. The authorities named the western spring “Seahorse Cold Spring” in honour of the vessel.

Combustible ice has already been discovered in more than 100 countries, buried in the Arctic ­permafrost and beneath the ocean floor.